1. Field of the Invention
The present invention relates generally to a switching circuit, and more particularly is directed to a switching circuit with a wide dynamic range using a junction type FET.
2. Description of the Prior Art
A switching circuit is proposed in the prior art as shown in FIG. 1. In the prior art switching circuit shown in FIG. 1, if FETs 1 and 2 are of a P-channel junction type, the FETs 1 and 2 are made conductive (on) when their gate electrodes are in the ground voltage, while they are made nonconductive (off) when their gate electrodes are in a plus voltage to achieve the switching operation.
With the prior art switching circuit shown in FIG. 1, in the case where the FETs 1 and 2 are made conductive, when an input voltage exceeds 0.7V (volts), the FETs 1 and 2 are biased forwardly between their gate-source by the input voltage to flow the gate current, so that at this time the part of the input voltage higher than 0.7V is clipped. That is, with the prior art switching circuit shown in FIG. 1, there is a defect that a clip may occur for a large input to narrow a so-called dynamic range.
Further, the impedance of the FETs 1 and 2 between their source-drain is fluctuated or changed by the level of an input signal, so that there may be produced much distortions.